Biography
i. Overview
ii. Boyhood days to appointment in the Royal Society (1643-1669)
iii. Scientific Growth
iv. As a highly paid government officer
Significant Contributions
i. The Reflecting Telescope
ii. Theory of Colour
iii. Principia
iv. Speed of Sound
v. Law of Cooling
References
i. Print materials ii. Online resources
BIOGRAPHY
Head and shoulders portrait of man in black with shoulder-length gray hair, a large sharp nose, and an abstracted gaze
Sir Isaac Newton, born in England in 1653, was undoubtedly one of the most significant figures in both his time and in all of History. He was most prominent in the fields of Physics, Mathematics and Astronomy, though he was, in addition, a theologist, natural philosopher and an alchemist. His greatest work, commonly referred to as the Principia, was published with the encouragement of Sir Edmond Halley, and is indisuputably among one of the most important books in the evolution of what we call "Science" today. It contained many of his findings and discoveries, with the more influential ones including the idea of a heliocentric universe, the laws of motion and gravity, as well as light. These were considered breakthroughs in his time, with many people before his work believing in outdated systems. Even in modern times, Sir Isaac Newton is still universally recognised and acknowlwedged as one of the most indisposable characters in human history, and the pioneer of science as we know it now. His studies shed light upon the mysteries of the phenomena of nature, and introduced a deeper, scientific explanation for things previously accepted at face value. The Principia is also said to be the foundation for classical mechanics. It revolutionised the way people thought of the universe, changed their mindsets, placed more importance on practical experimentation, and thus greatly advanced the Scientific Revolution. Here we divide his life into 3 distinct periods, each one significant to the development of his scientific genius and career in its own way.
Boyhood days to appointment in the Royal Society (1643-1669)
Newton's birthplace
Isaac Newton was born prematurely on the Christmas day of 1642 in the manor house of Woolsthorpe, Lincolnshire (pictured above). His father, whom he had never known, had been a wealthy yet completely illiterate man- he owned multitudinous property and animals but could not even sign his own name.
When he was barely three years old, Newton’s mother remarried and left him to the care of his grandparents. Isaac was denied emotional or parental care as a child, and grew up as the emotional equivalent of an orphaned child. His childhood was thus a conflicted and dark period of his life that developed his resentful and complex character, and possibly contributed to the stimulation of his mind.
When his mother returned, she observed that Newton showed little academic interest or promise, with negative reports from his schoolmasters. Subsequently she withdrew him from school to teach him to manage an estate as his father had, but this he also failed at. Later, he was re-enrolled in school to be prepared for entrance to university. Motivated partly by a desire for revenge against a schoolyard bully, he became the top-ranked student. He gained entrance to Trinity College Cambridge where his passion for learning was either ignited, discovered or both simultaneously, as can be seen by his admittance of valuing the pursuit of education above his religion:
"... setting my heart on money, learning, and pleasure more than Thee ..."
The curriculum at Cambridge, though well-taught, was somewhat conventional and antiquated. Newton was taught plenty regarding works by classical authors such as Aristotle. By all appearances his academic performance was mediocre at best- however it is now known that he had engaged in extensive private study of revolutionary scientific works such as those of René Descartes, Pierre Gassendi and Thomas Hobbes, and in particular Boyle. He noted his observations and the fascinating formation of his ideas in a book which he entitled Quaestiones Quaedam Philosophicae (Certain Philosophical Questions). He headed the book with a Latin statement meaning "Plato is my friend, Aristotle is my friend, but my best friend is truth" identifying himself as a philosophical scientist unfettered by convention from a young age.
Despite his seemingly mediocre academic performance, Newton was elected a scholar on 28 April 1664 and received his bachelor's degree in April 1665. For the next two years after, Cambridge was shut down due to widespread plague. Newton once again engaged in self-study, and, unrestricted by any curriculum or syllabus, it was during this period that his scientific genius emerged. In a period of less than two years, while Newton was still under 25 years old, he began a series of revolutionary advances in science- in particular the branches of mathematics, optics, physics, and astronomy. As he later said, 'All this was in the two plague years of 1665 and 1666, for in those days I was in my prime of age for invention, and minded mathematics and philosophy more than at any time since.'
After these two years, Newton returned to Cambridge. His reflecting telescope, constructed in 1668, brought him to the attention of the scientific community, and he was made a fellow of the Royal Society. From the mid-1660s, Newton had conducted a series of experiments on the composition of light, discovering that white light is composed of the same system of colours that can be seen in a rainbow and establishing the modern study of optics (or the behaviour of light). His more influential current position enabled him to circulate his findings, and in 1672, he published his first scientific paper on the nature of colour in the Philosophical Transactions of the Royal Society, that was as brilliant as it was controversial. The paper was generally well received, but certain scientists objected to the base theory of the paper that Newton had been attempting to prove by experiment alone: that rather than the motion of waves, light consists of the motion of small particles. Newton was constantly conflicted; while naturally he desired fame and recognition, he also harboured an irrational fear of criticism. Later in the late 1670s, after a tragic set of events pushed Newton over the edge, this fear of criticism would escalate into a crippling phobia of publishing papers.
Scientific growth
Newton's most monumental scientific publication
Upon publication of his paper, a controversy ensued and continued until 1678. Nonetheless, in 1675 Newton published yet another paper. This time it drew ungrounded charges of plagiarism of a celebrated curator of experiments. Dispirited Newton withdrew from publishing papers.
In 1678, Newton suffered a serious emotional breakdown, and in 1679 his mother passed on. Newton cut himself off from the outside world and buried himself in alchemical research. He conducted rigorous investigations into the hidden forces of nature, thereby opening theoretical avenues not found in the mechanical philosophy, the world view that had sustained his early work but now contradicted his findings. While the mechanical philosophy reduced all phenomena to the impact of matter in motion, the alchemical tradition upheld the possibility of attraction and repulsion at the particulate level. Newton's later insights in celestial mechanics can be traced in part to his alchemical interests. By combining action-at-a-distance and mathematics, Newton transformed the mechanical philosophy by adding a mysterious but no less measurable quantity, gravitational force.
In 1666, in one of the most classic and widely-known instances of scientific discovery, Newton observed the fall of an apple in his garden at Woolsthorpe. He later claimed, 'In the same year I began to think of gravity extending to the orb of the Moon.' However, evidence suggests that the concept of universal gravitation did not enter Newton’s head until 20 years later, and was ironically developed by the previous perpetrator of the controversy surrounding Newton’s published papers (Robert Hooke). In November 1679, Hooke initiated an exchange of letters that regarding the question of planetary motion. Hooke's letters provided a conceptual link between central attraction and a force falling off with the square of distance, which Newton grasped and from which he formed his own conclusion:
"... all matter attracts all other matter with a force proportional to the product of their masses and inversely
proportional to the square of the distance between them."
Later, in 1687, Newton published the Philosophiae naturalis principia mathematica or Principia (pictured above), which is recognized as the greatest scientific text in existence. This explained a wide range of previously unrelated phenomena: the eccentric orbits of comets, the tides and their variations, the precession of the Earth's axis, and motion of the Moon as perturbed by the gravity of the Sun.
This work made Newton an international leader in scientific research. While some scientists disagreed, this did not stop the universal admiration for Newton's technical expertise. This acclaim laid the groundwork for Newton’s later attainment of power and worldly success. In 1689 he was elected to represent Cambridge in Parliament, and also became acquainted with John Locke, the famous philosopher, and Nicolas Fatio de Duillier, a brilliant young mathematician.
In 1693, however, Newton suffered a severe nervous disorder, not unlike his earlier breakdown following his mother’s death. The cause is open to interpretation: overwork; the stress of controversy; the unexplained loss of friendship with Fatio; or perhaps chronic mercury poisoning, the result of nearly three decades of alchemical research. Each factor may have played a role. Shortly after his recovery Newton was appointed Warden and then Master of the Mint, which assured him social and economic status.
In 1703 Newton was elected president of the Royal Society, and was annually re-elected. In 1704 he published his second major work, the Opticks, based largely on work completed decades before. He was knighted in 1705.
As a highly-paid government officer
The Coat of Arms of the Royal Society
Although his creative years had passed, Newton continued to heavily determine on the direction and development of science. He played his profound influence over the Royal Society to his personal advantage. His tenure as president has been described as tyrannical and autocratic, and his control over the lives and careers of younger disciples was all but absolute. Although earlier in his life he had proven that he could not abide controversy or criticism, later, as president of the Royal Society, Newton marshaled all the forces at his command to achieve his singular goals. For example, he published Flamsteed's astronomical observations - the labor of a lifetime - without the author's permission; and in his dispute with Leibniz concerning the calculus, Newton enlisted younger men to fight his war of words, while behind the lines he secretly directed charge and counter-charge. In effect, the actions of the Society were little more than extensions of Newton's will, and until his death he dominated the landscape of science without rival.
He died in London on March 20, 1727.
SIGNIFICANT CONTRIBUTIONS
As referenced above, throughout his life Newton pioneered important scientific instruments and theories that would mark the turning point for the evolution of Science, and that our basic curriculum of Science now takes for granted. These are some monumental technologies that Newton's genius developed:
The Reflecting Telescope
A drawing of the Newtonian telescope
Newton improved on the refracting telescope of old based on his own theories of color and refraction. He realised that the fault lay not in the lens' shape, but rather the previously-overlooked differences in the lens' refraction of different-coloured lights. However, he made several hasty conclusions based on badly-made and -planned experiments and thought that the nothing could be done to improve the refracting telescope. For example, he believed that all refracting substances would diverge colours in a way that was proportional to their mean refractions, thus thinking that the refracting telescope could not be altered to be any more precise, despite its initial inaccuracies.
Fortunately, he didn't stop at that, but continued on to design a reflecting telescope, based on his theory of reflection, where every angle of incidence of any light, regardless of colour, was equal to its angle of reflection. And therefore, he began to experiment and select materials and shapes for his objective mirror. He decided upon speculum metal, an alloy of tin and copper, and devised methods to grind and polish them to a satisfactory degree. He also tried and tested different shapes and sizes, finally landing upon a spherical one, rather than a parabola like before, to make construction easier and reasoned that the faults of the refracting telescope was also due to the chromatic aberration (rather than spherical) of its objective mirror.
Along with this, he also had a secondary "diagonal" mirror near the primary mirror's focus to reflect the image capture at a 90-degree to an eyepiece mounted on the side of his Newtonian telescope, which allowed for minimal obstruction of the objective mirror.He also added a tube, a mount and fittings. With all of this, his first compact reflecting telescope had a mirror diameter of 1.3 inches and a focal ratio (focal length divided by the diameter of a mirror), and could see as far as the Galilean moons of Jupiter and the crescent phase of Venus. Pleased with his results, he was motivated to create a second telescope with an improved magnifying power of 38 diameters, which he then presented to the Royal Society of London in the December of 1672.
This telescope, till today, is still named the Newtonian telescope and was a major milestone in the creations of man with which one could finally see the universe and its true vastness.
Theory of Colour
A sketch by Newton of one of his prism experiments.
A sketch by Newton of one of his prism experiments
Besides his other contributions, Newton also advanced Physics in coming up with his Theory of Colour. He explored his theory through deformities and attributes of light rays [which have different colours], and after experimenting with intermediate angles of refraction, came up with a characteristic of these rays--they either agree or disagree proportionally. In other words, refraction is very precise and exact [meticulously so] and this finding enabled him to move onto the rest of his theory.
One rule he came up with was that the colour[s] of all natural bodies as we knew them were not due to anything else but that they reflected certain colours of light more so than others, causing them to be a unique shade of their own. Also, he concluded that if an equal quantity of each colour of light came together at the exact same angles, they would "diminish into whiteness". When this white light hit objects such as a clear prism, the different rays that had made up that white light would be broken up and refracted off once again in their separate colours. In short, Newton's theory of colour ruled that colours, as we perceived them, were made up of different ratios and quantities of different colours of light, due to the objects' varying natural ability to reflect and/or absorb some colours of light more so than others. This was based on his practical experiments [a key feature of the Scientific revolution], and his most fundamental finding that light was refracted in precise angles, and could either be broken up or combined together to form different colours.
Principia
Manuscript of Newton's Philosophiæ Naturalis Principia Mathematica
Newton's work, Principia, was published in 1687, eight years after his return to the study of gravity and mechanics. His work was written in reference to Kepler's laws of planetary motion, alongside correspondence with the Royal Society which was represented by Robert Hooke and their exchange of letters from between 1679 to 1680. Through these exchanges, Newton worked out a proof regarding centripetal force and the resulting elliptical orbits of planets.
In his work was the discovery of a concept called gravitas, which was to become our term "gravity", and it started the belief that such universal gravitation was at work all around us. In Principia, he entailed the three laws of universal motion that are used and have remained largely unchanged even now. Making use of a form of geometrical analysis much like calculus, he came up with the first calculations for the speed at which sound travelled through air. Besides this, he came up with the theory that although man had accepted the earth's shape to be spherical, the poles of the Earth were, in reality, "slightly flattened", similar to the equinoxes of the moon.
Using a calculus-like method of geometrical analysis, he also gave the first analytical determination of the speed of sound in air; inferred that the poles of the Earth, which is spheroidal in shape, were slightly flattened, based on the equinoxes of the moon. He continued in his pursuit of an explanation for the pheonomena of nature, by propsing various theories and starting further studies of the orbits and motion of bodies in space, such as planets. One of the strongest messages brought across in his book was his belief and advocation of the theory that the sun did not revolve around the earth, but rather, remained "at rest" while earth and other planets revolved around it. This was one of the most prominent contributions to proving the existence of a heliocentric universe.
This book, the Principia, was published at last with the encouragement of Edmond Halley. In its second edition, Newton refuted criticism and claims that he had been trying to introduce occult into science through his theory of "invisible forces acting across wide spaces", by defining the claims as "needlessly framing" theories unimplied by his laws. Despite this, however, his book gained him a circle of admirers and was said to be one of the most significant works during the period of the Scientific Revolution.
Indeed, Principia formed the basis for much of the Scientific Revolution with regards to astronomy, with Newton's proposal of the three laws of universal motion. They were perhaps, the most recognized and acclaimed of his findings, and combined with Kepler's earlier discoveries, managed to eradicate any remaining doubt in a heliocentric universe, advancing the scientific revolution greatly.
Speed of Sound
Published in Principia was one of Newton's key accomplishments, a determination of the speed of sound. Newton achieved this by measuring the time taken for an echo to return to him, using a pendulum. By dividing the total distance of sound traveled by the time needed for the sound to travel from the opposite end back to him, he found the length of time taken by varying the pendulum lengths and its period. Through his experimentation, he calculated the speed of sound to be between 920 to 1085 feet per second. Though the current accepted value differs by about 16 percent from his original calculation, using such basic equipment to make such a breakthrough was a major accomplishment at his time.
The discovery of the speed of sound allowed for better and more accurate measurements, as well as comparisons for speeds in space and allowed astronomers to progress in their discoveries. Based on this calculation, other speeds were able to be more accurately determined and this assisted in the scientific revolution.
Law of Cooling
Newton's law of cooling is something closely linked to several heat transfer theories formulated over time. He reasoned that the rate of heat loss of a body is proportional to the difference between the body's temperature and that of its surroundings. However, his law was somewhat incorrect as it is imprecise; whereas, an accurate formulae would require some form of analysis of hear flow, based on the often arbitrary heat transfer between a poor heat-conductive object (a human) and its surroundings.
REFERENCES Print Materials
James Gleick. Isaac Newton.Vintage Books: 2004. Print.
Sir Isaac Newton, I. Bernard Cohen, Anne Miller Whitman. The Principia: mathematical principles of natural philosophy. University of California Press: 1999. Print.
David Berlinski. Newton's gift: how Sir Isaac Newton unlocked the system of the world. Simon & Schuster: 2002. Print.
TABLE OF CONTENTS
i. Overview
ii. Boyhood days to appointment in the Royal Society (1643-1669)
iii. Scientific Growth
iv. As a highly paid government officer
i. The Reflecting Telescope
ii. Theory of Colour
iii. Principia
iv. Speed of Sound
v. Law of Cooling
i. Print materials
ii. Online resources
BIOGRAPHY
Sir Isaac Newton, born in England in 1653, was undoubtedly one of the most significant figures in both his time and in all of History. He was most prominent in the fields of Physics, Mathematics and Astronomy, though he was, in addition, a theologist, natural philosopher and an alchemist. His greatest work, commonly referred to as the Principia, was published with the encouragement of Sir Edmond Halley, and is indisuputably among one of the most important books in the evolution of what we call "Science" today. It contained many of his findings and discoveries, with the more influential ones including the idea of a heliocentric universe, the laws of motion and gravity, as well as light. These were considered breakthroughs in his time, with many people before his work believing in outdated systems. Even in modern times, Sir Isaac Newton is still universally recognised and acknowlwedged as one of the most indisposable characters in human history, and the pioneer of science as we know it now. His studies shed light upon the mysteries of the phenomena of nature, and introduced a deeper, scientific explanation for things previously accepted at face value. The Principia is also said to be the foundation for classical mechanics. It revolutionised the way people thought of the universe, changed their mindsets, placed more importance on practical experimentation, and thus greatly advanced the Scientific Revolution. Here we divide his life into 3 distinct periods, each one significant to the development of his scientific genius and career in its own way.
Boyhood days to appointment in the Royal Society (1643-1669)
Newton's birthplace
Isaac Newton was born prematurely on the Christmas day of 1642 in the manor house of Woolsthorpe, Lincolnshire (pictured above). His father, whom he had never known, had been a wealthy yet completely illiterate man- he owned multitudinous property and animals but could not even sign his own name.
When he was barely three years old, Newton’s mother remarried and left him to the care of his grandparents. Isaac was denied emotional or parental care as a child, and grew up as the emotional equivalent of an orphaned child. His childhood was thus a conflicted and dark period of his life that developed his resentful and complex character, and possibly contributed to the stimulation of his mind.
When his mother returned, she observed that Newton showed little academic interest or promise, with negative reports from his schoolmasters. Subsequently she withdrew him from school to teach him to manage an estate as his father had, but this he also failed at. Later, he was re-enrolled in school to be prepared for entrance to university. Motivated partly by a desire for revenge against a schoolyard bully, he became the top-ranked student. He gained entrance to Trinity College Cambridge where his passion for learning was either ignited, discovered or both simultaneously, as can be seen by his admittance of valuing the pursuit of education above his religion:
The curriculum at Cambridge, though well-taught, was somewhat conventional and antiquated. Newton was taught plenty regarding works by classical authors such as Aristotle. By all appearances his academic performance was mediocre at best- however it is now known that he had engaged in extensive private study of revolutionary scientific works such as those of René Descartes, Pierre Gassendi and Thomas Hobbes, and in particular Boyle. He noted his observations and the fascinating formation of his ideas in a book which he entitled Quaestiones Quaedam Philosophicae (Certain Philosophical Questions). He headed the book with a Latin statement meaning "Plato is my friend, Aristotle is my friend, but my best friend is truth" identifying himself as a philosophical scientist unfettered by convention from a young age.
Despite his seemingly mediocre academic performance, Newton was elected a scholar on 28 April 1664 and received his bachelor's degree in April 1665. For the next two years after, Cambridge was shut down due to widespread plague. Newton once again engaged in self-study, and, unrestricted by any curriculum or syllabus, it was during this period that his scientific genius emerged. In a period of less than two years, while Newton was still under 25 years old, he began a series of revolutionary advances in science- in particular the branches of mathematics, optics, physics, and astronomy. As he later said, 'All this was in the two plague years of 1665 and 1666, for in those days I was in my prime of age for invention, and minded mathematics and philosophy more than at any time since.'
After these two years, Newton returned to Cambridge. His reflecting telescope, constructed in 1668, brought him to the attention of the scientific community, and he was made a fellow of the Royal Society. From the mid-1660s, Newton had conducted a series of experiments on the composition of light, discovering that white light is composed of the same system of colours that can be seen in a rainbow and establishing the modern study of optics (or the behaviour of light). His more influential current position enabled him to circulate his findings, and in 1672, he published his first scientific paper on the nature of colour in the Philosophical Transactions of the Royal Society, that was as brilliant as it was controversial. The paper was generally well received, but certain scientists objected to the base theory of the paper that Newton had been attempting to prove by experiment alone: that rather than the motion of waves, light consists of the motion of small particles. Newton was constantly conflicted; while naturally he desired fame and recognition, he also harboured an irrational fear of criticism. Later in the late 1670s, after a tragic set of events pushed Newton over the edge, this fear of criticism would escalate into a crippling phobia of publishing papers.
Scientific growth
Newton's most monumental scientific publication
Upon publication of his paper, a controversy ensued and continued until 1678. Nonetheless, in 1675 Newton published yet another paper. This time it drew ungrounded charges of plagiarism of a celebrated curator of experiments. Dispirited Newton withdrew from publishing papers.
In 1678, Newton suffered a serious emotional breakdown, and in 1679 his mother passed on. Newton cut himself off from the outside world and buried himself in alchemical research. He conducted rigorous investigations into the hidden forces of nature, thereby opening theoretical avenues not found in the mechanical philosophy, the world view that had sustained his early work but now contradicted his findings. While the mechanical philosophy reduced all phenomena to the impact of matter in motion, the alchemical tradition upheld the possibility of attraction and repulsion at the particulate level. Newton's later insights in celestial mechanics can be traced in part to his alchemical interests. By combining action-at-a-distance and mathematics, Newton transformed the mechanical philosophy by adding a mysterious but no less measurable quantity, gravitational force.
In 1666, in one of the most classic and widely-known instances of scientific discovery, Newton observed the fall of an apple in his garden at Woolsthorpe. He later claimed, 'In the same year I began to think of gravity extending to the orb of the Moon.' However, evidence suggests that the concept of universal gravitation did not enter Newton’s head until 20 years later, and was ironically developed by the previous perpetrator of the controversy surrounding Newton’s published papers (Robert Hooke). In November 1679, Hooke initiated an exchange of letters that regarding the question of planetary motion. Hooke's letters provided a conceptual link between central attraction and a force falling off with the square of distance, which Newton grasped and from which he formed his own conclusion:
Later, in 1687, Newton published the Philosophiae naturalis principia mathematica or Principia (pictured above), which is recognized as the greatest scientific text in existence. This explained a wide range of previously unrelated phenomena: the eccentric orbits of comets, the tides and their variations, the precession of the Earth's axis, and motion of the Moon as perturbed by the gravity of the Sun.
This work made Newton an international leader in scientific research. While some scientists disagreed, this did not stop the universal admiration for Newton's technical expertise. This acclaim laid the groundwork for Newton’s later attainment of power and worldly success. In 1689 he was elected to represent Cambridge in Parliament, and also became acquainted with John Locke, the famous philosopher, and Nicolas Fatio de Duillier, a brilliant young mathematician.
In 1693, however, Newton suffered a severe nervous disorder, not unlike his earlier breakdown following his mother’s death. The cause is open to interpretation: overwork; the stress of controversy; the unexplained loss of friendship with Fatio; or perhaps chronic mercury poisoning, the result of nearly three decades of alchemical research. Each factor may have played a role. Shortly after his recovery Newton was appointed Warden and then Master of the Mint, which assured him social and economic status.
In 1703 Newton was elected president of the Royal Society, and was annually re-elected. In 1704 he published his second major work, the Opticks, based largely on work completed decades before. He was knighted in 1705.
As a highly-paid government officer
The Coat of Arms of the Royal Society
Although his creative years had passed, Newton continued to heavily determine on the direction and development of science. He played his profound influence over the Royal Society to his personal advantage. His tenure as president has been described as tyrannical and autocratic, and his control over the lives and careers of younger disciples was all but absolute. Although earlier in his life he had proven that he could not abide controversy or criticism, later, as president of the Royal Society, Newton marshaled all the forces at his command to achieve his singular goals. For example, he published Flamsteed's astronomical observations - the labor of a lifetime - without the author's permission; and in his dispute with Leibniz concerning the calculus, Newton enlisted younger men to fight his war of words, while behind the lines he secretly directed charge and counter-charge. In effect, the actions of the Society were little more than extensions of Newton's will, and until his death he dominated the landscape of science without rival.
He died in London on March 20, 1727.
SIGNIFICANT CONTRIBUTIONS
As referenced above, throughout his life Newton pioneered important scientific instruments and theories that would mark the turning point for the evolution of Science, and that our basic curriculum of Science now takes for granted. These are some monumental technologies that Newton's genius developed:
The Reflecting Telescope
A drawing of the Newtonian telescope
Newton improved on the refracting telescope of old based on his own theories of color and refraction. He realised that the fault lay not in the lens' shape, but rather the previously-overlooked differences in the lens' refraction of different-coloured lights. However, he made several hasty conclusions based on badly-made and -planned experiments and thought that the nothing could be done to improve the refracting telescope. For example, he believed that all refracting substances would diverge colours in a way that was proportional to their mean refractions, thus thinking that the refracting telescope could not be altered to be any more precise, despite its initial inaccuracies.
Fortunately, he didn't stop at that, but continued on to design a reflecting telescope, based on his theory of reflection, where every angle of incidence of any light, regardless of colour, was equal to its angle of reflection. And therefore, he began to experiment and select materials and shapes for his objective mirror. He decided upon speculum metal, an alloy of tin and copper, and devised methods to grind and polish them to a satisfactory degree. He also tried and tested different shapes and sizes, finally landing upon a spherical one, rather than a parabola like before, to make construction easier and reasoned that the faults of the refracting telescope was also due to the chromatic aberration (rather than spherical) of its objective mirror.
Along with this, he also had a secondary "diagonal" mirror near the primary mirror's focus to reflect the image capture at a 90-degree to an eyepiece mounted on the side of his Newtonian telescope, which allowed for minimal obstruction of the objective mirror.He also added a tube, a mount and fittings. With all of this, his first compact reflecting telescope had a mirror diameter of 1.3 inches and a focal ratio (focal length divided by the diameter of a mirror), and could see as far as the Galilean moons of Jupiter and the crescent phase of Venus. Pleased with his results, he was motivated to create a second telescope with an improved magnifying power of 38 diameters, which he then presented to the Royal Society of London in the December of 1672.
This telescope, till today, is still named the Newtonian telescope and was a major milestone in the creations of man with which one could finally see the universe and its true vastness.
Theory of Colour
A sketch by Newton of one of his prism experiments
Besides his other contributions, Newton also advanced Physics in coming up with his Theory of Colour. He explored his theory through deformities and attributes of light rays [which have different colours], and after experimenting with intermediate angles of refraction, came up with a characteristic of these rays--they either agree or disagree proportionally. In other words, refraction is very precise and exact [meticulously so] and this finding enabled him to move onto the rest of his theory.
One rule he came up with was that the colour[s] of all natural bodies as we knew them were not due to anything else but that they reflected certain colours of light more so than others, causing them to be a unique shade of their own. Also, he concluded that if an equal quantity of each colour of light came together at the exact same angles, they would "diminish into whiteness". When this white light hit objects such as a clear prism, the different rays that had made up that white light would be broken up and refracted off once again in their separate colours. In short, Newton's theory of colour ruled that colours, as we perceived them, were made up of different ratios and quantities of different colours of light, due to the objects' varying natural ability to reflect and/or absorb some colours of light more so than others. This was based on his practical experiments [a key feature of the Scientific revolution], and his most fundamental finding that light was refracted in precise angles, and could either be broken up or combined together to form different colours.
Principia
Manuscript of Newton's Philosophiæ Naturalis Principia Mathematica
Newton's work, Principia, was published in 1687, eight years after his return to the study of gravity and mechanics. His work was written in reference to Kepler's laws of planetary motion, alongside correspondence with the Royal Society which was represented by Robert Hooke and their exchange of letters from between 1679 to 1680. Through these exchanges, Newton worked out a proof regarding centripetal force and the resulting elliptical orbits of planets.
In his work was the discovery of a concept called gravitas, which was to become our term "gravity", and it started the belief that such universal gravitation was at work all around us. In Principia, he entailed the three laws of universal motion that are used and have remained largely unchanged even now. Making use of a form of geometrical analysis much like calculus, he came up with the first calculations for the speed at which sound travelled through air. Besides this, he came up with the theory that although man had accepted the earth's shape to be spherical, the poles of the Earth were, in reality, "slightly flattened", similar to the equinoxes of the moon.
Using a calculus-like method of geometrical analysis, he also gave the first analytical determination of the speed of sound in air; inferred that the poles of the Earth, which is spheroidal in shape, were slightly flattened, based on the equinoxes of the moon. He continued in his pursuit of an explanation for the pheonomena of nature, by propsing various theories and starting further studies of the orbits and motion of bodies in space, such as planets. One of the strongest messages brought across in his book was his belief and advocation of the theory that the sun did not revolve around the earth, but rather, remained "at rest" while earth and other planets revolved around it. This was one of the most prominent contributions to proving the existence of a heliocentric universe.
This book, the Principia, was published at last with the encouragement of Edmond Halley. In its second edition, Newton refuted criticism and claims that he had been trying to introduce occult into science through his theory of "invisible forces acting across wide spaces", by defining the claims as "needlessly framing" theories unimplied by his laws. Despite this, however, his book gained him a circle of admirers and was said to be one of the most significant works during the period of the Scientific Revolution.
Indeed, Principia formed the basis for much of the Scientific Revolution with regards to astronomy, with Newton's proposal of the three laws of universal motion. They were perhaps, the most recognized and acclaimed of his findings, and combined with Kepler's earlier discoveries, managed to eradicate any remaining doubt in a heliocentric universe, advancing the scientific revolution greatly.
Speed of Sound
Published in Principia was one of Newton's key accomplishments, a determination of the speed of sound. Newton achieved this by measuring the time taken for an echo to return to him, using a pendulum. By dividing the total distance of sound traveled by the time needed for the sound to travel from the opposite end back to him, he found the length of time taken by varying the pendulum lengths and its period. Through his experimentation, he calculated the speed of sound to be between 920 to 1085 feet per second. Though the current accepted value differs by about 16 percent from his original calculation, using such basic equipment to make such a breakthrough was a major accomplishment at his time.
The discovery of the speed of sound allowed for better and more accurate measurements, as well as comparisons for speeds in space and allowed astronomers to progress in their discoveries. Based on this calculation, other speeds were able to be more accurately determined and this assisted in the scientific revolution.
Law of Cooling
Newton's law of cooling is something closely linked to several heat transfer theories formulated over time. He reasoned that the rate of heat loss of a body is proportional to the difference between the body's temperature and that of its surroundings. However, his law was somewhat incorrect as it is imprecise; whereas, an accurate formulae would require some form of analysis of hear flow, based on the often arbitrary heat transfer between a poor heat-conductive object (a human) and its surroundings.
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